1. Field of the Invention
The invention relates particularly to an arrangement of a burner or heater for the reduction of the exhaust gas temperature which includes a combustion chamber which includes a combustion air blower, an electrical ignition device, a flame tube or heating tube and a heat exchanger whose indirect heat surfaces are spaced from and surround the flame tube concentrically, and an outlet tube for the combustion gas.
Linear heating devices are known for use in mobile units, such as motor vehicles, ships or caravans where they serve for the heating of the interior of the passenger spaces. The known heating devices use liquid fuel, preferably the fuel also used in the motor of the unit. The room can either be heated by means of hot air which is immediately blown into the space or indirectly by means of heated water. The water heating devices also allow for the preheating of the motor.
Such a heating device is described in detail in German patent publication 21 39 504. In this publication a heating device is described, which has a single cast metal piece forming the combustion chamber including the heat exchanger having indirect heating surfaces, such as ribs, on both sides of the flame tube and an exhaust gas exit tube. The flame tube is connected to the combustion chamber and protrudes into the heat exchanger part having the ribs. Such a device is designed for the heating of fresh air and serves the heating of the passenger room or space.
Such heating device has disadvantages with regard to the handling of the exhaust gas. The combustion gas exiting from the flame tube and diverted at the heat exchanger wall flows toward the exhaust gas exit tube in the shortest path possible, and only a minor part flows through the annular chamber between the flame tube and the heat exchanger along the ribs which are in the area facing the exhaust gas exit tube. An irregularity in the temperature distribution is the result, and due to the relatively short flow path of the exhaust gas the exhaust gas temperature at the exhaust exit is unnecessarily high.